DE2542841A1 - Process for the production of difficult to ignite to fire-resistant foam materials with a low volume weight - Google Patents

Description

geri NGEM density

The present invention relates to a process for the production of hard to ignite to fire-resistant foams, suitable for industrial purposes, for example in packaging technology, in traffic, in construction and the like.

Due to their thermal and sound insulation properties, synthetic foams are a sought-after material in the building industry, in cooling technology, in traffic and similar. The fundamental disadvantage of these substances, however, is their light weight Flammability and combustibility. The most common type of foam is expanded polystyrene. Its slight inflammation and flammability does not allow its thermal insulation properties to be fully utilized up to now. The problems the flammability also affect other foams to the same extent, such as foam polyvinyl chloride, foam polyurethanes, -polyamides, -phenoplastics and -epoxy resins.

In practical use, the combustible and ignitable

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degraded in several ways. Except the so-called ¹¹ sandwich process ", ie in addition to the combination with a non-flammable coating with various inorganic materials, flame-retardant substances, usually organic chlorine or bromine compounds, are added to the bulk of the polymer or to the monomer before the polymerization. Examples are tetrabromoxylene, Hexabromobenzene, tris (i, 3-dichloroisopropyl) phosphate, tetrabromobisphenol and the like. After foaming and pressing to the desired shape, the product acquires the so-called self-extinguishing character. Synthetic foams with this property start to burn on direct contact with the flame However, the burning of the material subsides after the flame has been removed. In a strong heat source, for example in a fire, the synthetic foams will burn even if they contain a flame retardant.

Urea-formaldehyde or melamine-formaldehyde type foams have a self-extinguishing character even without the addition of flame-retardant substances, however, it also has a lower structural strength, so that its practical application possibilities are limited are.

The above-mentioned disadvantages are avoided by the process according to the invention without the addition of flame-retardant substances eliminated. The hardly inflammable to fire-resistant foams with a density of 20 to 200 kg / nr at the same time have good structural strength, with the favorable heat and sound insulation properties remain.

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The inventive method for the production of hardly inflammable to fire-resistant foams, which with the addition of a solid foam filler, such as pre-expanded or expanded polystyrene or Foam polyurethane and a binder based on a melamino or melamino formaldehyde resin, or of a halogen-containing polymer is characterized in that said in the form an aqueous precondensate or an aqueous dispersion used binders in per se known Form foams by whipping or by introducing a compressed gas in the presence of a propellant and in the foam obtained in this way before the precondensate has hardened, if necessary before Coagulation of the dispersion mixes the particles of the above-mentioned foam filler out of the mixture excess water removed by pre-drying at temperatures below 100 ° C and then in a form in the Heat presses together with simultaneous curing or coagulation of the binder and refilling of the filler.

Amorphous silicon dioxide of natural origin or amorphous silicon dioxide, produced by chemical or metallurgical means, which may be 5 to 20% by weight hydrated Contains aluminum oxide, added.

Depending on the intended use, bactericidal, fungicidal, insecticidal or other pesticidal agents based on brominated salicylanilides, mercury or copper compounds, chlorinated phenols, mono-, di-, tri- or tetraorganotin compounds and the like, in an amount of 0.01 to 2.00 wt -.% enforce.

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By practical application of the parts and prefabricated components made of the foams according to the invention, a Achieve increased fire safety in traffic, in packaging technology and especially in construction. The incombustibility of foams, especially in the Sandwich shape, allows its application even on the highest floors of high-rise buildings, whatever due to a lower, static load on the building foundation and through other economic contributions, for example through lower energy consumption noticeable when heating the object.

Example 1:

To 280 parts by weight of a urea-formaldehyde precondensate, which is diluted with water in a ratio of 1: 1, a propellant is added, which is a contains acidic catalyst or which itself serves as an acidic catalyst, preferably an organic one Sulfonic acid, such as isopropylnaphthalene sulfonic acid, the is optionally partially neutralized to the sodium salt. The foaming is carried out by introducing Compressed air or an inert gas (carbon dioxide, nitrogen) with an overpressure of about 4.5 atu or by vigorously stirring the liquid mixture. Then mix before the precondensate hardens the pre-expanded polystyrene in an amount of 70 parts by weight. The beads of the pre-foamed Polystyrene will be evenly foamed with the enveloped aqueous binder. At the same time, the beads become an easily malleable mass connected. ,, which one is moderately at a temperature below

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Pre-dries 100 ° C, only to remove the excess water, but not so long that the rest of the propellant is removed in the polystyrene. Then the mixture is pressed in a mold and with direct Foamed steam at a temperature of 100 to 110 ° C .

Example 2;

To 385 parts by weight of a 50-6 strength aqueous dispersion of a copolymer of vinylidene chloride (55 %) and vinyl chloride (45 %) containing a common emulsifier and stabilizer (for example the commercially available product known under the trademark Sconatex) 100 parts by weight of the blowing agent according to Example 1 are added and the mixture is foamed by whipping. 350 parts by weight of the pre-expanded polystyrene are mixed in the resulting foam. After moderate pre-drying, the mixture is foamed in a mold and pressed with direct steam or with hot air at 100 to 110 ° C.

example 3 '

60 parts by weight of the propellant are added to 440 parts by weight of the aqueous dispersion listed in Example 2 Example 1 and foams the liquid by whipping. The foam formed is mixed with 50 parts by weight of the pre-expanded polystyrene. Thereafter, 150 parts by weight of a liquid urea-formaldehyde precondensate are added, diluted with water in a ratio of 1: 1, too. After stirring for a short time, not yet in hardened state, you are gradually with stirring 300 parts by weight of natural kieselguhr, which in addition to the amorphous silica about 20% by weight hydrated

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Contains alumina, too. After moderate pre-drying, the mixture is pressed into the desired shape in a Form by the action of direct steam or hot air, at a temperature of 100 to 110 C together. Alternatively, the mold can be heated indirectly from the outside during the pressing process.

The process cited in the examples can be converted in various ways within the scope of the invention. For example, vinylidene chloride copolymers can also be used in the form of, above all, such aqueous suspensions which, after drying and even at ordinary temperature, form cohesive films. Instead of the pre-expanded or completely expanded polystyrene, for example, a foam styrene copolymer with 20 to 40 wt .-? 6 acrylonitrile, also the foam polyvinyl chloride, produced with the help of blowing agents, foam polyurethanes, phenol-formaldehyde resins and similar resins or foam epoxy resins, optionally mixtures of these substances, use. Diatomaceous earth and related fillers can also be added before or at the same time as the foam filler is added. The pre-drying can be carried out on sieves in the air or in a drying system or on a movable sieve belt machine, if necessary in another conventional way. The advantage of Verwednung of aqueous binder dispersions represents the perfect homogenization, the water remaining in the removal in the final phase at temperatures above 10O ⁰ C to complete heat penetration, foaming and curing, if appropriate for coagulation of the binder and its connection with the filler contributes.

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Claims (4)

- ψ - claims 1. A process for the production of flame-retardant to fire-resistant foams with a low density using a solid foam filler, such as prefoamed or foamed polystyrene or foam polyurethane and a binder based on a urea or melaminoforinaldehyde resin or a halogen-containing polymer, characterized in that the above-mentioned Binders or mixtures thereof, used in the form of an aqueous precondensate or an aqueous dispersion, foams in a manner known per se by whipping or by introducing a compressed gas in the presence of a propellant and in the foam obtained in this way before the precondensate hardens, optionally before coagulation the dispersion interfere the particles of the above-mentioned foam filler removed from the mixture through liquid water through pre-drying at temperatures below 100 ⁰ C and then in a form of heat, with simultaneous Aushär processing, or coagulation of the binder and possible refilling of the filler compresses. 2. The method according to claim 1, characterized in that the mixture is amorphous silicon dioxide of natural origin, for example diatomaceous earth, adds. 3. The method according to claim 1, characterized in that the mixture is amorphous silicon dioxide, produced by chemical or metallurgical means, which may hydrate 5 to 20% by weight Contains aluminum oxide, adds. 7098 U / 1003 4. The method according to claim 1 to 3, characterized in that the mixture is bactericidal, fungicidal, insecticidal or other pesticidal agents based on brominated salicylanilides, mercury or Copper compounds, chlorinated phenols, mono-, di, tri- or tetraorganotin compounds and similar, added in an amount of 0.01 to 2.00 wt .-%. 709814 / 100-3